Fix what the first Android run found

The flow ran on a Pixel 9a and its emulator (2026-10-02); what it found:

- The composer stayed on the card just written after "New flashcard", and
  on the original after "Duplicate": leaving a card changed the state
  before the new one was in it, so the screen took the new card for gone.
  It now waits for the card it asked for.
- Bottom sheets reached under the status bar with the keyboard open
  (useSafeArea).
- The field being written stayed behind the keyboard: the editor scrolls
  only within itself, so the card face now keeps it in view when it opens
  and when the keyboard rises, as a text field does.
- A tap on read-only rich text put a caret in it and opened the keyboard on
  phones, and in the composer never opened the field. RichContentView is
  display only now: no selection, taps go to what surrounds it, a sound's
  button still plays (decided 2026-10-02).
- The card types broke their names on a phone; they are choice chips that
  wrap (decided 2026-10-02).
- The week overview marked days before the person's first activity as
  missed; they show nothing now. An import starts the activity too, without
  counting as studying (decided 2026-10-02).
- A composer preview cut short gave no sign of it; it fades out over its
  last 32 dp, only when cut short (decided 2026-10-02).
- "Isn't on this device yet" showed for any image or sound that failed;
  a file that is here but can't be decoded now says so, and offers no retry.
- The signed-in account card was narrower than the anonymous one.
- The composer's title said "Create flashcards" also when opened on a
  stored card; it says "Edit flashcards in …" then (decided 2026-10-02).
- The Anki fixtures carry a valid PNG and a silent MP3, so they also serve
  to try the import by hand (decided 2026-10-02); regenerated with Anki
  26.9.3.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/lib/l10n/app_localizations_en.dart

@@ -522,6 +522,14 @@ class AppLocalizationsEn extends AppLocalizations {
     return 'Create flashcards for \"$title\"';
   }
 
+  @override
+  String get composerEditTitle => 'Edit flashcards';
+
+  @override
+  String composerEditTitleFor(String title) {
+    return 'Edit flashcards in \"$title\"';
+  }
+
   @override
   String get composerSaving => 'Saving…';
 
@@ -1179,6 +1187,10 @@ class AppLocalizationsEn extends AppLocalizations {
   String get fileImageUnavailable =>
       'This image isn\'t on this device yet. It shows once it\'s uploaded and you\'re online.';
 
+  @override
+  String get fileImageUnreadable =>
+      'This image can\'t be shown. Its file may be damaged, or in a format this device can\'t read.';
+
   @override
   String get fileFromElsewhere => 'Files from the web aren\'t shown.';
 
@@ -1192,6 +1204,10 @@ class AppLocalizationsEn extends AppLocalizations {
   String get fileSoundUnavailable =>
       'This sound isn\'t on this device yet. It plays once it\'s uploaded and you\'re online.';
 
+  @override
+  String get fileSoundUnplayable =>
+      'This sound can\'t be played. Its file may be damaged, or in a format this device can\'t play.';
+
   @override
   String get ankiImportMenu => 'Import from Anki';